The invention is based on an adjustment device of the type described by the preamble to the main claim. Adjustment devices of this kind, in known forms of embodiment, are realized as reversable electromotors having a subsequent gear drive and a potentiometer for the detection of the adjustment angle as a feedback value for a followup amplifier, which furnishes the supply voltage for the electromotor. If a throttle device in a bypass around the throttle valve of an internal combustion engine is to be adjusted with an adjustment device of this kind, for instance to effect closed-loop control of the idling rpm of the engine, then at the present time not only are strict demands placed on the electric/electronic portion of the adjustment device but the control of the bypass cross section must be made as precise as possible, because regulations concerning exhaust composition are becoming more and more stringent and the need to conserve fuel is ever more apparent.